Producers are assessing whether a project fits their slate, their budget band and their next eighteen months. Most approaches never address any of the three.
A producer reading an unsolicited approach is answering a practical question: can this film be financed at a level my company works at, within a timeframe that fits my slate?
That is why relevance beats enthusiasm. A short note demonstrating why this project belongs next to two of their previous titles does more than a long pitch.
They are also assessing the filmmaker: how clearly the project is understood, whether the stage is described honestly, and whether the materials are consistent with each other.
Everything above is knowable in advance from credits, budget bands and recent activity. Which makes producer outreach a research task before it is a persuasion task.